The invention relates to a metal static seal of hollow annular type for providing sealing under severe conditions of use, typically at temperatures that are very high or very low, at high pressures, and for large diameters, such as in aviation and space environments.
The seal is said to be “static” because such a seal is used in configurations where there is no moving part in contact therewith. Static sealing is then provided. The drawback of such seals is that they are difficult to fabricate since they are usually made by machining, which is an operation that is found to be lengthy and expensive.
That is why, in application FR 2 800 147, the Applicant has proposed an annular metal static seal that can be made simply by stamping.
Nevertheless, although seals of that type are inexpensive to produce, they do not present a profile of sufficient strength to withstand in combination very high pressures and large diameters in applications that require high performance sealing (such as all the other seals presently used in the production of aeroengines, which tend to suffer excessive plastic deformation, i.e. deformation that has a harmful impact on the performance of the seal, in particular in terms of its usable restitution).
The term “very high” pressure is used to mean pressures of several hundred bar (typically greater than 2×107 Pascals), depending on the dimensions and the substrate material used.
The term “large” diameters is used to mean diameters greater than 200 millimeters (mm) or indeed greater than 1 meter (m).
An application that requires “high performance sealing” is an application that presents:                a low leakage rate (of the order of 108 normal cubic centimeters per second and per millimeter of circumference (Ncm3/s/mm));        a high level of usable restitution (ability of the seal to follow any movement of its interfaces while remaining leaktight); and        an ability to operate over a large temperature range (which may go from the cryogenic range, at around 20 kelvins (K), to high temperatures, higher than 1000 K).        